1. Field of the Invention
The present invention generally relates to a color thermal printer of a type which utilizes a color ink ribbon having ink areas of different color alternating over the length thereof for the reproduction of a color image on a sheet material.
With the color thermal printer to which the present invention pertains, an image of a desired color can be obtained on the sheet material by successively transferring thermally fusible ink pigments of different color from a web of pigment carrier, forming a part of the color ink ribbon, onto the sheet material so as to superimpose with each other thereby to permit mixture of these different colors to represent the desired color. However, the term "color thermal printer" herein referred to for the purpose of the present invention should not be construed as limitative of the printer having only the capability of printing an image in a plurality of colors which solely depends on the type of ink ribbon. For example, when a monochromatic, for example, black, ink ribbon is used, the color thermal printer can give a print-out of a black image, but when a multi-color ribbon is used, it can give a print-out of a colored image.
2. Description of the Prior Art
A variety of color thermal printers are available in the commercial market. An example of the prior art color thermal printers is shown in FIG. 3 of the accompanying drawings in schematic block representation.
The illustrated prior art color thermal printer comprises a reader unit including an image scanner 21 for reading, for example, a color document and for providing a data descriptive of the color document and a memory 22 for the storage of the data fed from the image scanner 21, and a printer unit including a printer control 23, a printer drive circuit 24, a thermal printing head 25, a particular color ink ribbon 26, a platen 27 and a platen drive motor 28 drivingly coupled with the platen 27.
The color ink ribbon 26 utilizable in the color thermal printer is currently available in a number of different types: A first one of these types is a three-color ink ribbon comprised of a length of pigment carrier sheet and cyclically alternating ink areas each including three ink layers of three different colors, for example, yellow, magenta and cyan, laid over the entire length thereof. A second one of these types is a four-color ink ribbon comprised of a length of pigment carrier sheet and cyclically alternating ink areas each including four ink layers of four different colors, for example, yellow, magenta, cyan and black, laid over the entire length thereof. A third one of these types is a monochromatic ink ribbon comprised of a length of pigment carrier sheet and a monochromatic, for example, black, ink layer laid over the entire length thereof.
Once a particular type of ink ribbon is mounted in the color thermal printer, the actual printing is carried out by the thermal printing head 25 in dependence on the data supplied from the memory 22. Where the ink ribbon actually mounted is either the first type or the second type, some or all of the pigments of the different colors are successively transferred from the associated ink layers onto a sheet material so as to superimpose one over the other to give a particular color substantially faithful to the color connoted by the data fed from the reader unit to the printer unit.
The first to third types of ink ribbon referred to above are in practice interchangeably used depending on the purpose for which the printing is desired.
Accordingly, where these different types of ink ribbon are available for one and the same color thermal printer, the user of the thermal printer is required to provide to the printer control instructions indicative of a particular one of these types that is actually loaded on the printer. In other words, according to the prior art color thermal printer, the user of the printer must manually input from a printer control panel to the printer control a command indicative of the particular one of these types of ink ribbon each time one type of ink ribbon is replaced with another one of the types, or the printer will fail to give an intended printing result.
One problem with the prior art color thermal printer is that, in spite of the requirements of the printer to be instructed as to the type of ink ribbon actually loaded thereon, the user of the printer often forgets to provide the necessary command to the printer control. This of course results in the improper printing result or the failure of the printer to operate properly.